我通过AJAX加载元素。其中一些只有当你向下滚动页面时才能看到。有什么方法可以知道元素现在是否在页面的可见部分?
当前回答
唯一适用于我的解决方案是(当$("#elementToCheck")可见时返回true):
$ (document) .scrollTop () + window.innerHeight + $ (" # elementToCheck ") .height () > $ (" # elementToCheck ") .offset直()上
其他回答
我改编了这个简短的jQuery函数扩展,你可以自由使用(MIT许可)。
/**
* returns true if an element is visible, with decent performance
* @param [scope] scope of the render-window instance; default: window
* @returns {boolean}
*/
jQuery.fn.isOnScreen = function(scope){
var element = this;
if(!element){
return;
}
var target = $(element);
if(target.is(':visible') == false){
return false;
}
scope = $(scope || window);
var top = scope.scrollTop();
var bot = top + scope.height();
var elTop = target.offset().top;
var elBot = elTop + target.height();
return ((elBot <= bot) && (elTop >= top));
};
function isScrolledIntoView(elem) {
var docViewTop = $(window).scrollTop(),
docViewBottom = docViewTop + $(window).height(),
elemTop = $(elem).offset().top,
elemBottom = elemTop + $(elem).height();
//Is more than half of the element visible
return ((elemTop + ((elemBottom - elemTop)/2)) >= docViewTop && ((elemTop + ((elemBottom - elemTop)/2)) <= docViewBottom));
}
检查元素是否在屏幕上,而不是公认的检查div是否完全在屏幕上的方法(如果div比屏幕大,这将不起作用)。在纯Javascript中:
/**
* Checks if element is on the screen (Y axis only), returning true
* even if the element is only partially on screen.
*
* @param element
* @returns {boolean}
*/
function isOnScreenY(element) {
var screen_top_position = window.scrollY;
var screen_bottom_position = screen_top_position + window.innerHeight;
var element_top_position = element.offsetTop;
var element_bottom_position = element_top_position + element.offsetHeight;
return (inRange(element_top_position, screen_top_position, screen_bottom_position)
|| inRange(element_bottom_position, screen_top_position, screen_bottom_position));
}
/**
* Checks if x is in range (in-between) the
* value of a and b (in that order). Also returns true
* if equal to either value.
*
* @param x
* @param a
* @param b
* @returns {boolean}
*/
function inRange(x, a, b) {
return (x >= a && x <= b);
}
我需要检查可滚动DIV容器内元素的可见性
//p = DIV container scrollable
//e = element
function visible_in_container(p, e) {
var z = p.getBoundingClientRect();
var r = e.getBoundingClientRect();
// Check style visiblilty and off-limits
return e.style.opacity > 0 && e.style.display !== 'none' &&
e.style.visibility !== 'hidden' &&
!(r.top > z.bottom || r.bottom < z.top ||
r.left > z.right || r.right < z.left);
}
我正在寻找一种方法来查看元素是否即将进入视图,所以通过扩展上面的代码段,我设法做到了。我想我应该把这个留在这里,说不定能帮到谁
Elm =是视图中要检查的元素
scrollElement =你可以传递window或者带有滚动的父元素
Offset =如果你想让它在元素在屏幕前200px处触发,那么传递200
isscro冷景的功能(elem, scrole,抵消) { var $elem = $(elem); var $window = $); var docViewTop = $window.scrollTop(); var docViewBottom = docViewTop + $window.height(); var elemTop = $elem.抵消()top; var elemBottom = elemTop + $elem.height() 归来((elemBottom +) > = docViewBottom) &&偏移(elemTop-offset) < = docViewTop) | | ((elemBottom-offset) < = docViewBottom) && (elemTop +偏移)> = docViewTop); 的